Timing issues?

[bulkin'up73chevy]

Hi guys been a long time since i've posted on here the whole busy life thing keeps tying me up.

I finally pulled my 86 out of the shop to get her going again. And low and behold that mean dealing with the issues that hid her there in the first place.


Truck info.

1986 C20
second owner
california emissions.
350 rochester carb on top.
There is no ecu. just smog equipment.

The Problem

3 years ago the truck started missing/backfiring. throwing fire out the exhaust horribly. and up the top. I took the truck to a local shop seeing as i'm no expert just a usual diy.er. They first said the cam was bad. pulled it out inspected it, and it was fine. rebuilt the carb. Put a new timing chain on. adjusted timing. same problem.... called me a month later and told me to get it off there lot with no change. and stole my exhaust. Now getting back into her. Today I put fresh fuel, and oil. and she sounds alright but still the same as 3 years ago. any idea to the issue?